Electronic Structure of Exciplexes and the Role of Local Triplet States on Efficiency of Thermally Activated Delayed Fluorescence

Chapran, Marian; Sahalianov, Ihor; Karaush-Karmazin, Nataliya N.; Wiosna-Salyga, Gabriela; Glowacki, Ireneusz; Luszczynska, Beata; Pander, Piotr; Baryshnikov, Glib V.

Abstract

In this work, we present an investigation of the electronic states in a series of thermally activated delayed fluorescence (TADF) exciplexes formed with the popular electron-transport compound TpBpTa and hole-transporting TCTA, TAPC, TPD10, TPD, and NPB. We rationalize the photophysical behavior of exciplexes by using computational methods and demonstrate that the reason for the commonly observed temporal red shift in the time-resolved spectra is related to the distribution of molecular conformations, thus CT energy, in film. We also use spectrally resolved thermoluminescence (SRTL) measurements to give insight into the trapping phenomena in exciplex blends. The results demonstrate that trapped charge carriers in the majority of studied exciplexes recombine through the luminescent intermolecular CT state. In addition, we report OLED devices using the said exciplexes in the emissive layer. The best performance is obtained with the TCTA:TpBpTa and TAPC:TpBpTa exciplexes showing maximum external quantum efficiencies (EQEs) of 8.8% and 7.2%, respectively.

Citation

Chapran, M., Sahalianov, I., Karaush-Karmazin, N. N., Wiosna-Salyga, G., Glowacki, I., Luszczynska, B., …Baryshnikov, G. V. (2023). Electronic Structure of Exciplexes and the Role of Local Triplet States on Efficiency of Thermally Activated Delayed Fluorescence. ACS Applied Electronic Materials, 5(3), 1489-1501. https://doi.org/10.1021/acsaelm.2c01518

• Journal Article Type: Article
• Acceptance Date: Feb 7, 2023
• Online Publication Date: Feb 20, 2023
• Publication Date: 2023
• Deposit Date: Apr 27, 2023
• Publicly Available Date: Apr 28, 2023
• Journal: ACS Applied Electronic Materials
• Print ISSN: 2637-6113
• Electronic ISSN: 2637-6113
• Publisher: American Chemical Society
• Peer Reviewed: Peer Reviewed
• Volume: 5
• Issue: 3
• Pages: 1489-1501
• DOI: https://doi.org/10.1021/acsaelm.2c01518
• Public URL: https://durham-repository.worktribe.com/output/1175039